Apple's been working away patching the Mac Pro firm ware again. I just installed the firmware patch they had from earlier this week and now today I get this:

I'm not sure what these provide yet. Here is what the installer says:
"The SMC Firmware Update adjusts fan behavior in the Mac Pro. The updater application will be installed in the /Applications/Utilities folder. Please follow the instructions in the updater application to complete the process".
The security update seems to be for the airport, which I never installed.

Update: This appears to be the same update from earlier in the week. The strange thing is that I already applied that update and received the comforting message telling me my Mac Pro firmware was up to date. This one, however, was applied without having to hold down the power button on the front. It was a smooth auto install. So maybe they are slightly different. I don't care enough to check and my machine is running exactly the same anyway.